The present disclosure relates generally to automated material handling systems and, in particular, to methods, systems, and computer program products for managing movement of work-in-process (WIP) materials in an automated manufacturing environment.
In a production environment, quantities of materials are transported through a defined route in an automated manufacturing line, e.g., among processing units, as well as temporary storage locations (e.g., stockers) situated within the route where the materials await further transport and processing. Oftentimes, there are instances where the materials sit idle in these storage locations until a production machine, or processing unit, is ready to receive them. When there is a large amount of materials in a given manufacturing line, the local stockers can become filled to capacity and the production area becomes backed up. Automated material handling systems (AMHSs) provide some assistance in managing the transport of these materials within a production area. AMH systems generally consist of material handling equipment and a material control system. The material handling equipment manages the flow of materials, while the control system manages the flow of information relating to these materials. Where an automated material handling system (AMHS) is employed, these idle materials are often automatically transferred to central storage when a stocker is full, regardless of whether the materials will be needed by the production line soon.
When a manufacturing line is shut down, either by a planned maintenance, retooling, or by unforeseen circumstances, the production materials may be subject to various degrees of degradation. For example, in a semiconductor fabrication facility, certain production materials, such as chemically treated wafers, if left exposed in a location within the production route for a specified period of time, may suffer oxidation or similar types of hazards. Depending upon the length of the equipment shutdown period, the results can be devastating, particularly when expensive production materials need to be scrapped as a result of damage due to environmental exposure. Moreover, the costs of additional cycle time and reduced equipment utilization exacerbate this problem.
What is needed, therefore, is a way to manage the movement of production materials in an automated manufacturing line that preserves the integrity of the production materials during shut down of the processing equipment in the manufacturing line.